Microbicidal gel found to lower HIV infection

New Delhi: In a breakthrough that will hearten those combating HIV among women—said to be at the highest risk of infection—scientists report that women who used a vaginal gel tinged with a microbicide cut infection rates by 39% over those who used a placebo.

The study, to be published in the journal Science on Friday, tested 889 women in South Africa over 30 months. If the same results can be replicated in a larger trial, vaginal gels could emerge as a viable alternative to other measures such as male circumcision and condom use to stem the HIV-AIDS epidemic, experts said.

The latest estimates from India’s National AIDS Control Organisation say that 2-3.1 million Indians are HIV-positive. Although male patients generally outnumber women in Africa, health experts say South Africa and India face common challenges in stemming the spread of HIV. “As in Africa, men in high-risk groups rarely use condoms. So any alternative solution is always welcome and can go a long way in combating the HIV epidemic,” said Sanjay Mehendale, a senior scientist at the National Aids Research Institute, Pune.

He added that at least three previous trials involving similar gels were unsuccessfully tried in India. “This is the first time that a phase-III trial has succeeded. So it makes sense to extend these studies to India too,” Mehendale added.

Around 2.7 million people are freshly infected with AIDS each year, and new methods are needed to curb the epidemic that still ravages countries in sub-Saharan Africa. Previous gels relied on drugs that weren’t specifically designed to target HIV, the virus that causes AIDS. The new approach, in which medicines are used before sex to prevent infection, is also being tested with antiviral pills and rings inserted vaginally once a month, eliminating the need to use the gel every time women have sex.

The vaginal gel contains Gilead Sciences Inc.’s AIDS drug Viread and it’s the first time such a product has protected women after six previous gels failed.

“Without the gel, 10 out of every 100 women were infected. The gel brought the number down to six and that’s worth taking this study forward,” said Salim S. Abdool Karim, one of the key scientists associated with the study, said in a telephone conference.

The authors also report 54% fewer infections among those who used the gel more than 80% of the time and a 28% reduction among those who used it less than 50% of the time.

“This study has established proof of concept that a vaginal microbicide containing an ARV (antiretroviral) can protect women from HIV. This is an incredibly important achievement. For all of us in the HIV prevention field, this result has shown that it may be possible to leverage this initial success using a single ARV at the time of sex into more potent approaches that could be 50%, 60% or even 70% effective for prevention of HIV. The results of this study have reinvigorated the field,” Sharon Hillier at the University of Pittsburgh School of Medicine, and principal investigator of the Microbicide Trials Network, told Science magazine.

Karim also pointed to the fact that none of the women involved developed resistance to the drug over the study period—a strong indicator of its reliability.

The gel was developed by Conrad, a non-profit organization funded by the US government and the Bill and Melinda Gates Foundation, under royalty-free licence from California-based Gilead, the world’s biggest maker of AIDS medicines.